3 Gallon Bags

Is it OK to flower in three gallon bags? I have them in 3 gallon bags right now with a 50/50 mix of light warrior and high quality organic potting soil. I had planned to move them to 10 gallon bags but the soil is so damned expensive I'm having second thoughts.

If I feed with Pureblend Pro Bloom will it be ok to leave them in the bags? I hear different things about how much space the roots need and I'm confused.

Thanks

They dont need as much as most people say, 3 gallon bags would hold a nice plant.

Thanks. I ended up getting bigger bags.